For example, “c” indicates the process is using the file system as its current directory while “m” indicates that the process is using a file mapped with mmap.

The old UNIX file permission system is commonly the only method of access control that people use. The basic file ownership permissions (user, group, and world/other) on UNIX are a bit outdated.

Whether you are using the command as input or output depends on whether you use the fileref in a reading or writing operation. For example, if the fileref is used in an INFILE statement, then the SAS ...